How is dengue diagnosed?

Doctors use symptoms and lab tests to confirm dengue, especially in people who live in or have recently travelled to areas where dengue is common. The choice of test depends on how many days you have been sick and local medical guidelines.

1. Symptoms to Watch

Common symptoms include:

• Sudden high fever
• Severe headache
• Pain behind the eyes
• Muscle and joint pain
• Nausea or vomiting
• Skin rash

Seek medical care immediately if you notice the following warning signs of severe dengue:

• Stomach (abdominal) pain or tenderness
• Persistent vomiting
• Bleeding gums or nose
• Blood in vomit or stool (black, tarry stools)
• Difficulty breathing
• Extreme tiredness, restlessness, or irritability

2. Lab Tests

Doctors choose tests based on how long you’ve had symptoms.

Early stage (first 5–7 days of illness)

• NS1 antigen test
  Detects dengue virus proteins in the blood.
• PCR test
  Detects dengue virus genetic material (RNA), usually done in specialized laboratories.

Later stage (after about 5–7 days)

• IgM antibody test
  Shows a recent dengue infection.
• IgG antibody test
  Shows a past infection. A rapid rise can suggest a repeat (secondary) dengue infection.

Test choice and timing can vary by country and test availability. A single negative test does not always rule out dengue, so doctors may repeat or combine tests if needed.

These tests confirm whether you have dengue, but they do not by themselves show how severe the illness is. Doctors combine test results with your symptoms, examination, and vital signs to decide on the best care.

3. Why Testing Matters

Early and appropriate testing helps:

• Confirm dengue and rule out other causes of fever
• Prevent complications by allowing closer monitoring
• Guide proper treatment (for example, fluids and monitoring rather than unnecessary injections)
• Reduce unnecessary medicines, such as antibiotics that do not work against viruses
• Support public health teams in tracking outbreaks and guiding mosquito control efforts